The Deadly Truth: A History of Disease in Americaby Gerald N Grob352pp, Harvard, £23.50

Some years ago I attended a conference called "Clinical Futures", at which various medical luminaries were invited to address the audience on the future of medicine and medical care. I recall a disconcertingly young, and disconcertingly famous, professor of medicine from a London teaching hospital offering a post-genomic view of the future, in which a single blood test would reveal not only what diseases we were suffering from, but the exact treatment that would successfully treat that disease if and when it were to appear.

The audience was swept along by the force of his rhetoric and visions of the brave new disease-free world, until his triumphal climax in which he promised that in the post-genomic world we would have no need of public health physicians and their tedious exhortations to live healthier lifestyles, which had done absolutely nothing whatever to combat disease. The next speaker quietly pointed out that in the 100 years before we had even heard of the human genome, public health measures had doubled life expectancy in this country, which wasn't bad going; but our medical Pangloss had already left for the airport.

Gerald Grob, the elder statesman of American medical history, was not present at that meeting, but has attended many similar gatherings. His majestic history of disease in America, beginning in its pre-Columbian past, and ending in the post- Aids era, is a welcome and scholarly antidote to such utopian thinking. Quoting Rene Dubois's 1961 text on science and utopia, he warns against such colossal misunderstanding of the nature of the relationship between man and disease.

Just as generals are accused of fighting the last rather than the next war, so are doctors doomed to tackle the last public health problem, not the next one. The great infectious pandemics, which wrought such destruction on the native Americans from 1492 onwards, are things of the past, but just as medicine was gaining the upper hand, new challenges from the chronic killers, such as heart disease and cancer, appeared.

Grob's analysis is not a pessimistic one, but realistic. He readily charts and salutes the progress made by medical science, less in vanquishing disease than in alleviating its burdens and suffering. Medicine is not, as the late Roy Porter had us believe, "the greatest benefit to mankind", but it is still a more than worthwhile endeavour in reducing human distress and the misery of illness. It is the assumption that medical progress will eventually eliminate disease altogether that really raises Grob's scholarly eyebrows.

As society transforms, so will disease, in new and unexpected ways. It was impossible to foresee that changes in sexual freedoms and practices would lead to the HIV epidemic among the gay community, nor how modern air conditioning would expose those attending the Philadelphia reunion of the American Legion to a hitherto unknown pathogen, now called Legionnaire's disease.

On a larger scale, urbanisation and the rapid development of early 19th-century America led to greater prosperity, and hence should have improved health, but in fact it did the reverse, exposing the new city-dwellers to the hazards of overcrowding and new occupational diseases, which it would take the best part of a century of public health measures to combat.

Surveying the present, Grob notes the remarkable changes in health that have occurred during his lifetime (he has recently retired from the chair of medical history at Rutgers). Infant mortality continues to decline. The average lifespan continues to increase, forcing us to redefine the concept of "old", as we have recently witnessed with the news that the retirement age for public sector workers is to rise by five years.

Should we therefore be happier? It seems not. Grob notes that "improved longevity, paradoxically, is accompanied by fears and anxiety about the future. An increasingly sophisticated diagnostic and imaging technology, aggressive marketing of drugs and other substances, a proliferation of epidemiological studies purporting to identify numerous dangers to health, and exploitation of these findings by the media - all combined to create concern that impersonal forces were having a detrimental impact on health".

Medicine and public health hand in hand have indeed conquered those diseases that devastated North and South America after the arrival of the Europeans, but HIV is now ravaging sub-Saharan Africa. Perhaps we are winning the "war against cancer" (although Grob has serious doubts on that score), but we are losing the war on depression, and are only just beginning to reflect on why we are being challenged by conditions seemingly unknown to previous generations - chemical sensitivities and chronic fatigue syndromes.

We have been encouraged to believe that all things are possible and that, given sufficient time, money and access to the right technologies, disease will become a thing of the past. Not so - Grob concludes by observing how "the disappearance of one category of disease invariably sets the stage for the emergence of another". The future histories of medicine will contain just as many diseases as their predecessors, but they will be different in ways we cannot imagine, no matter how many conferences we attend on "clinical futures".

· Simon Wessely is professor of psychiatry at King's College London and the Institute of Psychiatry